Electrostatic coating systems having bell cups that rotate at high speeds to atomize liquid coating material are known. In some electrostatic coating systems, liquid coating material is fed onto an inner surface of the rotating bell cup through a feed tube that extends along the axis of rotation of the bell cup. Forces created by the rotating bell cup act on the liquid coating material causing a film of coating material to be formed over the inner surface of the bell cup. The film of coating material flows along the inner surface of the bell cup toward a forward, discharge edge of the bell cup and a voltage source electrostatically charges the flowing film of coating material. At the discharge edge of the rotating bell cup, the film of coating material is discharged as an electrostatically charged mist which is directed toward an oppositely-charged object to be coated.
It is desirable for electrostatic coating systems to apply an even coating of material to the objects being coated. However, in some conventional electrostatic coating systems, clumps of partially dried coating material build up on the end of the feed tube adjacent the rotating bell cup. From time to time, the built up paint drops from the end of the feed tube onto the rotating bell cup and is flung onto an object being coated and creating a defect in the coating which needs to be buffed, or otherwise removed from, the object during rework operations performed subsequent to the coating process. It is therefore, desirable to reduce paint buildup on the ends of feed tubes of rotary atomizers.